MANCHESTER, N.H. — New Hampshire has all the conditions in place for an insurgent conservative to catch fire. If only Newt Gingrich — or anyone else — would strike a match.

There’s precious little time left for a candidate to emerge on Mitt Romney’s right and become the latest presidential upstart to challenge the political establishment in New Hampshire, a state that has propelled more than its fair share of underdogs to national prominence.

Gingrich, politicos here say, has largely failed to capitalize on the once-electric interest in his candidacy with a clear economic message and the personal presence New Hampshire voters expect. Without a deeply rooted local base of support, Gingrich won’t have this state to fall back on if his prospects continue to falter in Iowa and nationally.

“He seems to be squandering a unique opportunity that was handed to him by the voters,” said Rich Killion, a former Tim Pawlenty adviser who worked for Romney’s 2008 campaign. “He had to follow up with making the case directly to the voters, day in, day out, making their concerns his concerns.”

“You can’t do that when you’re signing books at Mount Vernon,” Killion said. “It’s day-in, day-out specifics on how his economic plan is going to create jobs and how he is going to stop the overspending in Washington. People aren’t looking for a history lesson here, on how Jefferson would do it.”

Though it’s viewed as the most moderate of the early primary states, New Hampshire should be prime territory for a conservative insurrection: Voters here elected huge Republican majorities in the state House and Senate last year, approving an ascetic, budget-slashing GOP platform that would make congressional Republicans swoon. And Granite Staters have a history of smacking back establishment favorites, voting for the populist Pat Buchanan in 1996 and the maverick John McCain in 2000 and again in 2008.

If Gingrich’s arrival as a national front-runner can be traced to a single moment, it is probably the Sunday after Thanksgiving, when he won the endorsement of the Union Leader, New Hampshire’s highest-circulation newspaper and a tribune of ideological conservatism. Suddenly, it looked plausible that Gingrich could score an upset in Iowa and then power through New Hampshire as a unifying figure on the right.

But Gingrich waited 15 days to visit the state, cresting in his momentum at a massive rally in Windham on Dec. 12. Gingrich has been in the state just once since then, for a visit this Wednesday that lasted only hours.

The Union Leader has continued to boost Gingrich, sometimes on the front page, but Republican leaders say that only goes so far when the candidate won’t also put his own effort into driving the campaign forward.

“If I’m in that position [of getting the Union Leader endorsement], if I’m advising a campaign, that next day I’m in the state for three days and I’m walking around with the Union Leader next to my head, kind of like that Harry Truman picture,” said Derry town GOP chairman Jim Foley. “There are people that are working very, very hard for this. Nobody works harder than Gov. Romney. Nobody works harder than Sen. Santorum. That’s what needs to be done and that’s what’s not happening.”

Travis Blais, who heads the Windham GOP, said Gingrich’s visit to the town represented a “high point because there was a lot of pent-up demand.”

“Before he sort of started that surge in the polls, he had done very little retail in New Hampshire. He had appeared at events like ‘Politics and Eggs’ and Chamber of Commerce functions,” Blais said, predicting that Gingrich isn’t finished yet: “I think you’re seeing the natural result of scrutiny of Gingrich. I wouldn’t say that Gingrich is ruined in New Hampshire at all. He still represents, to New Hampshire voters, the conservative alternative to Mitt Romney.”

But thanks to a barrage of Iowa attack ads from Romney supporters and his own inaction here, Gingrich’s path through the early states appears to be closing — and it will get narrower still if Ron Paul hangs on to first place in Iowa. Gingrich’s operation in New Hampshire has improved, but it’s not the political firewall he’d need to reverse a loss of momentum in the caucuses.

Foley, who is neutral in the primary, filed a complaint against the Gingrich campaign last week for allegedly making improper robocalls to voters on a do-not-call list, and left no question about how he assesses the Gingrich team.

“You look at a candidate that has a reputation for exaggeration, for being unapologetic, for being somewhat divisive — he has surrounded himself with a staff that is the exact same way,” Foley said, adding of the Gingrich operation: “A whole lot of this is a bit of smoke and mirrors — social media, Facebook, Twitter.”

Gingrich was in Manchester this week to collect the endorsement of New Hampshire House Speaker Bill O’Brien, a strident conservative whom even admirers say exemplifies both the victories and the excesses of the state’s 2010 GOP takeover.

O’Brien wasn’t the only iconic midterm election figure at the event: Gingrich’s state director, the youthful conservative organizer Andrew Hemingway who made his name in 2010, introduced him at the downtown Radisson. Former state GOP Chairman Jack Kimball — a onetime tea party candidate for governor ousted from the state party due to financial mismanagement — also circulated in the audience.

Former state legislator Kevin Smith, a Republican running for governor in 2012, said there was “natural, built-in support for someone like Newt Gingrich” in the Granite State.

“New Hampshire voters like politicians who are frank, who will just tell it to them like it is, and I think Gingrich has been doing that on the stump,” Smith said, cautioning: “I don’t know if Gingrich fits that mold as well as McCain did.”

If Gingrich has surrounded himself with some of the trappings of last year’s New Hampshire Republican wave, including the Union Leader’s lavish praise, he hasn’t succeeded in galvanizing a genuine conservative coalition behind his campaign. The most recent polls show him running third in the state, behind Romney and Paul, whose campaign has run negative spots against Gingrich in New Hampshire.

Part of the reason for that, Republicans suggest, is that Gingrich has always been an imperfect candidate to capture the insurgent spirit of 2010.

“I don’t think most people would think of him as an outsider,” said Republican state Rep. Will Smith, a lead sponsor of the “right to work” proposal that triggered a showdown this year between the New Hampshire Legislature and Democratic Gov. John Lynch.

Smith, a Rick Perry supporter, said there was still no candidate who had convinced voters that he is a staunch conservative — and viable to win the nomination and the White House.

“I think the appeal of somebody who, in your gut you feel has a real shot at winning, who is a conservative, would probably rally them,” Smith said. “I think it’s that hunger for somebody that is able to stand up to what I consider the chopping block of the media.”

Hillsborough GOP Chairman Steve Stepanek, a state representative backing Gingrich, argued that his candidate is the only one in the field who still has an opportunity to seize that space against Romney, and predicted that Gingrich would put in some of the sweat equity that’s been missing from his effort so far.

“I would expect to see that he’s going to be spending more time here, that he’s going to be doing more town hall events reaching out to the people,” Stepanek said. “If he spends a lot more time in New Hampshire, which is what he’s planning on doing, and they get to see him and hear from him up close, they’ll realize how good he really is.”

For Gingrich, though, time is running out, and New Hampshire isn’t the only priority on his agenda, or even the most immediate one. He’s spending Friday in South Carolina and then launching a post-Christmas bus tour of Iowa on Dec. 27.

That means he’ll be counting on a solid Iowa performance to propel him into New Hampshire, and then an intense one-week push to close the deal.

Gingrich appeared to lower expectations for his performance in New Hampshire and other early states during a Thursday appearance in Virginia, declaring that he needed to finish strong in Iowa and crack “the top two in New Hampshire and then to win South Carolina and Florida.”

“We have a huge ground game in New Hampshire, which just sprung up overnight, I think largely in reaction to Massachusetts,” Gingrich said, in a dig at Romney’s home state.

Romney’s supporters openly scoff at the idea that a powerful grass-roots operation has suddenly come into being for their opponent, and express confidence that they’ve built a New Hampshire organization that can withstand whatever even a rebounding Gingrich can throw at them.

“Mitt is holding very, very well here,” said New Hampshire House Majority Leader D.J. Bettencourt, a Romney supporter, who acknowledged that the Union Leader endorsement was “a positive development for Newt.”

“The problem is that his campaign has completely failed to take advantage of it,” Bettencourt said. “The Union Leader can print as many editorials as they want and the Gingrich campaign still isn’t going to be able to close the gap.”